Impregnation of cotton materials



atenteci Apr. 7, 1936 1 OFFICE fifi36124 REGNATIUN F BUTTON MATERIALS @arl l. Malm, Rochester, N. ill, assignor to East-- man Kodak Company, Rochester, N. 'iL, a corporation of New York No Bra. Application April it, i933,

Serial No. M6335 5 ill.

The prment invention relates to the pregnation of cellulose materials such as cloth, thread, par, etc. which comprises swelling the material with for instance a mercerizing hath prelnary to the impregnation thereof with an oraanic solvent solution of a cellulose ester or ether.=

heretofore cotton threads or filaments have hcen suhiected to a shower or spray of a cellulose derivative solution which process resulted merely in a product comprising a core of the cellulose material entirely surrounded hy a coati of the cellulose derivative, however, the amount of impregnation of the cellulose material, if n merely incidental to that coatina operation. a Une ohiect of my invention is to prepare a cotton material which has heen impregnated with a solution of a cellulose derivative in the sense that the cellulose derivative will he oy distrihuted therethru. dnoerohject of my invention is to provide a process of preparing impreanated cotton material in which the cotton 'terial is preliminarily prepared to he highly ,septihle to the subsequent treatment with an oruc solvent solution of a cellulose derivative. it further ohject of my invention is to provide a process for preparing a cotton material treated with a cellulose derivative solution which sliders from prior art processes which disclose the formation of a skin only onv the surface of the flher without any appreciable impregnation talring place.

l have found that a satisfactorily impreanated cotton material may he formed upon its treatment with an orlganic solvent solution of a cellulose ester or other if the cotton material is t suhiected to'a swelling treatment. I have found that this swelling of the fibers of the cotton is solvent, preferably that employed for dissolving f the cellulose derivative to form the solution which is subsequently applied thereto. it is of course recognized that if any of the organic solvents which may he employed do have a swelling action on cotton material, this dehydration step would he unnecessary, altho at the present time no such'organic solvent is known. I have found tt the product resulting from my invention is a material more resistant to water than the original cotton material and in addition possesses a heat ohtained by a mercerization treatment. it

(W. til-lid) high l'mtre thereby enhancing the appearance of the original material.

process comprises first prelirily suhjecting the cotton material to he impregnated to the action of a swelling agent such as by a mercerization treatment. For example the cotton may he placed in a dilute (525% alkali) aqueous solution of an alkali metal 'hydromde and may he allowed to remain therein and soak for a few hours, the time of treatment, of course, varying with the concentration. if an aqueous or some otherswelling agent not compatible with the cellulose derivative solution later to he applied, is used, the nicer after the memorization treatment must he washed to free the there of the liquid employed for the mercerization. This washing may he with water to remove all of the swelling agent from the nhers. This washi is followed by a dehydration of the cotton material such as by means of an orgc solvent to remove suhstantially all of the moisture therefrom. it is. important'however that .this dehydration is not a drying as the fibers should he wet with the organic solvent which was employed to elrpelthe water. it is preferred that the orcanic solvent used he the one which is employed as the solvent for preparing the cellulose derivative solution which is to he app to the l rial. The thus swelled and dehydrated, hut not dry, cotton terial is then ready to he impreg-- mated. with an organic solvent solution of a cellulose ester such as cellulose acetate, cellulose acetate propionate or cellulose acetate stearate or a cellulose ether such as ethyl cellulose or henzyl cellulose. d plasticiaer is usually added to this solution.

s impregnation is best accomplished by immeming the cotton terial in a dilute solution of the cellulose derivative for a time depending on the viscosity and penetrating speed of the so-. lution. After the cotton material is thoroughly impregnated thruout it may he removed from the cellulose derivative solution; the, excess solution y be removed therefrom and the solvent is then removed such as by evaporation. The product formed if the starting material was thread is eminently suited for use for electrical insulation.

If the starting material when cotton cloth or fabric the resulting product is an imitation linen while a water-resistant paper is produced when paper is employed as the starting material. Oloviously the products of my invention may he em- The following example illustrates the application of my invention to the preparation of a moisture-resistant thread.

Cotton thread was immersed in a aqueous sodium hydroxide solution at 10 C. for 4 hours. The thread was then washed with water until the alkali was thoroughly removed whereupon the thread was washed with acetone to remove the water present therein. It was then immersed in a 2% solution of cellulose acetate in acetone for about half an hour, was centrifuged and dried.

In the process of my invention various equivalents may be employed. For instance instead of cotton other cellulose material such as paper and the like may be employed as the material to be impregnated. As pointed out above various organic cellulose derivatives other than celluloseacetate such as cellulose acetate propionate, cellulose acetate butyrate, cellulose butyrate, cellulose acetate stearate, ethyl cellulose, benzyl cellulose etc. may be employed as the impregnating material. 7

In the present process any organic solvent which is a solvent for the cellulose derivative employed will be suitable providing this solvent can be separated from the material after impregnation thereof. A volatile solvent such as acetone is for this reason preferred. Other solvents which would come into use in this connection, the sole criterion being whether the cellulose derivative is soluble therein, are: ethylene chloride, propylene chloride, methyl acetone, methyl acetate, ethylene chloride-methyl alcohol etc.

Other swelling agents than aqueous sodium hydroxide such as aqueous potassium hydroxide, suggest themselves as of value in the present invention supplementary to or as an equivalent of aqueous sodium hydroxide.

The concentration of the solution of the organic derivative of cellulose which is employed for impregnating the cellulose material may be varied as desired by the individual operator however it 1. The process of impregnating a cotton material with an ether or an organic acid ester of cellulose which comprises swelling the material with dilute aqueous alkali, washing the material with water, removing the water therefrom with a non-aqueous liquid and, while the material is still wet with the non-aqueous liquid, treating it with an amount of a dilute solution of an ether or an organic acid ester of cellulose, in an organic solvent, suiflcient to impregnate the material.

2. The process of impregnating a cotton material with cellulose other which comprises swelling the material with dilute aqueous alkali, washing the material with water, removing the water therefrom with a non-aqueous liquid and, while the material is still wet with the nonaqueous liquid, treating it with an amount of a dilute solution of cellulose ether, in an organic solvent, suflicient to impregnate the material.

3. The process of impregnating a cotton material with an organic ester of cellulose which comprises swelling the material with dilute aqueous alkali, washing the material with water, removing the water therefrom with a non-aqueous liquid and while the material is still wet with the non-aqueous liquid, treating it with an amount of a dilute solution of an organic ester of cellulose, in an organic solvent, sufllcient to impregnate the material.

4. The process of impregnating a cotton material with a cellulose acetate stearate which comprises swelling the material with dilute aqueous alkali, washing the material with water, removing the water therefrom with a non-aqueous liquid and, while the material is still wet with the nonaqueous liquid, treating it with an amount of a dilute solution of a cellulose acetate stearate, in an organic solvent, suilicient to impregnate the material.

5. The process of impregnating a cotton material with an ether or an organic acid ester of cellulose which comprises swelling the material with dilute aqueous alkali, washing the material with water, removing the water therefrom with acetone and, while the material is still wet with the acetone, treating it with an amount of a dilute solution of an ether or an organic acid ester of cellulose, in an organic solvent, sufllcient to impregnate the material.

CARL J. MALM. 

